Diatoms as ecological indicators of water quality assessment in adihalli lake, Gandasi lake and halagenalli lakes of Arasikere Taluk, Hassan District, Karnataka, India

Ecological indicators have pervasive appeal to scientists, environmental managers and general public at large. They have long been used to detect changes in nature, but scientific maturation in indicator development has occurred mainly in the past twenty years. Currently, indicators are primarily used to assess condition of the environment, as early-warning signals of ecological problems. The present survey reveals the presence of diverse diatom communities in three lakes consisting of 9 different genera and 15 species. Anthropogenic activity was drastically increased in winter season in all the three lakes than in summer season. Synedra ulna (SULN) in Adihalli lake and Navicula halophila (NHAL) in Halagenahalli lake indicated the disturbances in lakes due to human activity and Navicula mutica (NMUT) considered as organic pollution indicators in polluted lakes. Highest number of 63,000 populations was found to be Cocconeis placentula (CPLA) in summer and 21,000 Navicula arabica (NARA) in winter of Adihalli lakes. In Gandasi lake summer season was predominated with Actinocyclus ehrenbergii (AEHR) with 42,000 and winter season with Navicula rhynocephalia (NRHY) with a population of 8,400. Similar size of population Pinnularaia acrosphaeria (PACR) of 42,000 in both winter and summer seasons was found in Halagenahalli Lake. Overall known diatoms are predicted as water quality indicators varied with their populations at winter and summer seasons.